My gas gauge in the elco does not work, yall know what a pain that can be in a daily driver. If you look at the gas gauge the needle is penned all the way over to the idiot light (about an inch past full). Does this sound like a bad sending unit or bad gauge? How can I tell for sure. I already checked the sending unites ground and wires they all look good and I cleaned the ground

It is actually an open connection between the gauge and sender. It could be the sender or just a wiring problem. Ground the brown wire that attaches to the sender, if the gauge goes to empty it is in the sender.